igneous
Granite and Pumice
Granite (plutonic rock) and Pumice (volcanic glass)
Granite: Hardness 6-7, salt-and-pepper appearance, phaneritic texture. Pumice: Hardness 5-6, grayish-white, vesicular (porous) texture, very low specific gravity.
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Physical properties
Granite: Hardness 6-7, salt-and-pepper appearance, phaneritic texture. Pumice: Hardness 5-6, grayish-white, vesicular (porous) texture, very low specific gravity.
Formation & geological history
Granite forms from the slow cooling of magma beneath the Earth's surface. Pumice forms from explosive volcanic eruptions where frothy lava cools rapidly in the air.
Uses & applications
Granite is widely used in construction, countertops, and monuments. Pumice is used as an abrasive, in lightweight concrete, and for horticultural purposes.
Geological facts
Pumice is the only rock that can float on water due to its trapped gas bubbles. Granite makes up the majority of the Earth's continental crust.
Field identification & locations
Identify granite by its visible interlocking crystals of quartz, feldspar, and mica. Identify pumice by its lightweight feel and sponge-like holes (vesicles). Found globally in volcanic or mountainous regions.
